The vascular endothelial cell, strategically located at the interface between vascular tissue and the circulating blood, is endowed with unique biological properties which enable it to modulate hemostasis. Studies here will investigate the impact of percussion trauma on selected hemostatic properties of cerebrovascular endothelium ex vivo (arterial and venous) using a human vessel segment model developed in our laboratory. During the course of these studies, a percussion trauma chamber will be developed in which vessels can be subjected to sublethal injury in a controlled experimental setting. The effects of trauma on the fibrinolytic potential (t-PA, u-PA and PAI-1) and procoagulant properties (tissue factor, formation of the prothrombinase complex and Factor X activation) of cerebral endothelial cells will be quantitatively delineated; reversibility of trauma-induced injury will be determined; and the efficacy of intervention with various agents administered to the test system prior to and following injury will be evaluated. It is anticipated that new information will be elucidated regarding the hemostatic response of the cerebrovascular endothelial cell to trauma. Approaches for recovery may be crucial in the development of therapeutic strategies designed to prevent the sequelae of secondary hemostatic complications induced by trauma to the brain.